Britain’s first field trial of genetically modified wheat has ended in disappointment as it failed to deter aphids as was hoped.

Scientists at Rothamsted Research used modified wheat to give off an odour that repelled aphids in the laboratory, but it did not repel the pests in the field.

In addition, the odour-emitting plants failed to attract natural aphid predators, such as ladybirds and parasitic wasps, to feed on the pests.

However, the two-year trial ending in 2013 at Rothamsted’s Hertfordshire headquarters did show GM wheat produced “significant quantities” of the aphid alarm pheromone.

Rothamsted scientists think the aphids – which can be major pest in wheat – may have become used to the constant production of this pheromone.

Lead scientist Toby Bruce, who spend days observing the aphids in the field, said their reaction to the odour might be akin to people ignoring a car alarm that never stops ringing.

“The smell might have disturbed them a bit to begin with, but it didn’t deter them enough,” Dr Bruce told Farmers Weekly.

Scientists said the challenge now is to alter the timing of the alarm signal from the plant to a burst in response to a threat rather than a continuous release.

The trial was set up to find a wheat crop that repel pests, using the non-toxic odour (E)-β-farnesene which is a naturally occurring chemical found in peppermint plants, rather than blanket spraying with insecticides.

However, anti-GM groups slammed the trial as a “waste of taxpayers’ money”.

“With GM crops it’s always jam tomorrow and never jam today,” said GeneWatch UK director Dr Helen Wallace.

Soil Association policy director Peter Melchett added that aphids are not a big problem for UK wheat crops as organic farmers, using no insecticides, do not have significant problems.

* The results of the study are published in the Scientific Reports journal.

Background to the Rothamsted trial

• Security around the GM wheat trial site cost about three times more than the research costs, figures reveal.  
• The research project cost £732,000, but as additional £1,794,439 was spent on security measures to keep protestors out, including CCTV, 24-hour manned security on site and 2.7m high perimeter fencing.
• Rothamsted scientists made a direct plea in a video posted on YouTube to anti-GM campaigners not to destroy their field experiment.
• Protest group Take the Flour Back had threatened to rip up the trial during a mass protest held outside the site in May 2012.
• A heavy police presence of up to 500 officers backed by a court order secured by Rothamsted prevented the group from destroying the crop.
• Anti-GM protestor Hector Christie climbed the fence and pulled up part of the crop and scattered organic wheat seed before he was arrested.
• The government funded the five-year project through the Biotechnology and Biological Sciences Research Council (BBSRC).